As the use of metallic orthopaedic implants for the treatment of fractures and the long term replacement of bones and joints continues to increase, it is becoming increasingly important to understand the mechanisms of metal corrosion in biological applications and to understand the biological reactions to corrosion production. Recent publications have indicated that corrosion rates measured in the laboratory do not reflect the corrosion rates measured in animals. The proposed research is designed to improve our understanding of the interactions between corrosion processes and biological fluids, especially proteins, and our understanding of the effects of corrosion products on bones and healing fractures. An interdisciplinary team will utilize techniques of mechanical engineering, materials science, and biology to address the questions. Laboratory experiments are proposed to study the process of fretting corrosion of implants in different protein solutions to identify the nature of the interactions. Electron spectroscopy (ESCA and AES) and biological test methods will be utilized to characterize the bonding between metals and proteins. Mechanical testing will be performed to develop a biomechanical model of a broken bone stabilized with a fracture fixation plate, which can be utilized to determine how plates should be applied to minimize the amount of corrosion. Animal experiments will be conducted to verify these results. Animal experiments will also be conducted to determine the detailed tissue response to metal implants, and the functional and biomechanical effects of reactions to metals used for internal fixation of fractures. Special tests on tissue and blood cells will be conducted to determine if the local reactions to implants have any affect on cells in other parts of the body. The long term goals are to develop laboratory tests which can be used to more accurately predict the amount a metal would corrode as an implant, to determine if certain metals should be avoided in the design and manufacture of new implants, and to develop more accurate methods for testing for reactions to metals.